FOOD MOTIVATION IN RATS OF DIFFERENT AGES

In this study, we attempted to compare food motivation in Brown-Norway rats of three different ages (8, 14, and 26 months old) under two dif ferent levels of food deprivation by measuring running speed in a runw ay. Food motivation was also assessed in a progressive ratio schedule of reinforcement in an operant chamber at one level of deprivation. Co mpared with the adult and middle-aged rats, the old rats had a slower running speed in the runway and made fewer leverpresses in the progres sive ratio test. It was suggested that both age and weight affected th e level of food motivation. A differential food deprivation technique (i.e., an age-related increase in the percentage of body weight reduct ion) may possibly be a way to reduce differences in levels of food mot ivation in rats of different ages.